<?phpuse Illuminate\Database\Eloquent\Model;class refundlogModel extends Model{	protected $table 		= 'refund_log';	public	  $primaryKey	= 'id';    public $timestamps = false;    protected function serializeDate($date)    {        return $date->format('Y-m-d H:i:s');    }    // 获取退款单号    public static function getSn($user_id)    {        $rand = $user_id < 9999 ? mt_rand(100000, 99999999) : mt_rand(100, 99999);        $order_sn = date('Yhis') . $rand;        $id = str_pad($user_id, (24 - strlen($order_sn)), '0', STR_PAD_BOTH);        return 'R' . $order_sn . $id;    }}